Mechanical properties of strands in a composite cable for robot arms under bending load

In recent years, population decline in developed countries has led to labor shortages, increasing the demand for industrial robots. However, their complex movements and repetitive use contribute to high failure rates in critical components, particularly conductive cables in robot arms. Ensuring cable quality is essential for improving reliability and performance. Since cables have various design parameters, relying solely on physical experiments increases time and costs. To address this, this study focuses on numerical analysis before experimental validation. A beam element model considering strand twisting was developed using Python, and bending loads were applied. The numerical results revealed that tensile and compressive stress varies depending on the strand position. In the outer strand, tensile and compressive stresses were mixed in the central and outer wires, resembling beam bending behavior. In the central strand, the deformation was constrained by twisting, forming a compressive stress field dominated by the minimum principal stress. These findings highlight the mechanical characteristics of cable strands under bending loads, contributing to the optimization of cable designs for industrial robots.